1998 JAGUAR X308 fuel pressure

Yes
R
EPAIR the high resistance circui
t. For additional information, refer to the wiring diagrams. CLEAR
the DTC. TEST the system for normal operation.
No GO to U2
.
U2: CHECK T H
E MECHANICAL GUARD SENSE
CIRCUIT FOR SHORT TO HIGH VOLTAGE
Re
connect the battery negative terminal.
1
Turn the ignition swi
t
ch to the ON
position.
2
Measure t
he voltage between PI42, pin 01 (BY) and GROUND.
3
Is the volt

age greater than 10 volts?
Yes REPAIR the short circuit. For addi tional information, refer to the wiring diagrams. CLEAR the DTC.
TEST the system for normal operation.
No GO to U3
.
U3: CHECK T H
E MECHANICAL GUARD SE
NSE CIRCUIT FOR SHORT TO GROUND
Turn the ignition swit
ch to the OFF
position.
1
Measure t
he resistance between PI42, pin 01 (BY) and GROUND.
2
Is
t
he resistance less than 10,000 ohms?
Yes REPAIR the short circuit. For addi tional information, refer to the wiring diagrams. CLEAR the DTC.
TEST the system for normal operation.
No GO to U4
.
U4: CHECK THE MEC H
ANICAL GUARD SENSOR POWER SUPPLY CIRCUIT
Re
conn
ect the ECM electrical connector, EM11.
1
Turn the ignition swi
t
ch to the ON
position.
2
Measure t
he voltage between PI42, pin 04 (UW) and GROUND.
3
Is th
e volt
age less than 5 volts?
Yes
REPAIR the power supply circuit. This circuit includ es the ECM. For additional information, refer to
the wiring diagrams. CLEAR the DTC. TE ST the system for normal operation.
No INSTALL a new mechanical guard sensor. CLEAR the DTC. TEST the system for normal operation.
PINPO
INT TEST V : DTC P1240, P1241, P1242
; SENSOR REFERENCE VOLTAGE MALFUNCTION,
HIGH/LOW VOLTAGE (THROTTLE SENSORS, FUEL TANK PRESSURE SENSOR)
TE S
T
CONDITIONS
D E
TAILS/RESULTS/ACTIONS
V
1
: CHECK THE REFERENCE VOLTAGE AT TH
E APP SENSOR/MECHANICAL GUARD SENSOR
Disc
onnect the APP sensor electrical connector, PI42.
1
Turn the ignition swi
t
ch to the ON
position.
2
Measure the voltage between PI
42,
pin 04 (UW) and GROUND.
3
Is th
e volt
age less than 5 volts?
Yes GO to V2
.
No
GO to V3
.
V2
: CHECK THE APP SENSOR/MECHA
NICAL GUARD SENSOR REFERENCE VOLTAGE CIRCUIT FOR HIGH
RESISTANCE
Di sc
onnect the battery negative terminal.
1
D
i
sconnect the ECM electrical connectors, EM10 and EM11.
2
Me
asure
the resistance between PI42, pin 04 (UW) and EM10, pin 21 (UW).
3
Me
asure
the resistance between PI42, pin 04 (UW) and EM11, pin 08 (UW).
4
Is either resi
stance greater
than 5 ohms?
Yes REPAIR the high resistance circui t. For additional information, refer to the wiring diagrams. CLEAR
the DTC. TEST the system for normal operation.
No GO to V3
.
V3
: CHECK THE APP SENSOR/MECHA
NICAL GUARD SENSOR REFERENCE VOLTAGE CIRCUIT FOR SHORT TO
HIGH VOLTAGE

R
econnect the battery negative terminal.
1
Turn the ignition swi

tch to the ON
position.
2
Measure the
voltage between PI
42, pin 04 (UW) and GROUND.
3
Is th
e voltage greater than 6 volts?
Yes REPAIR the short circuit. For addi tional information, refer to the wiring diagrams. CLEAR the DTC.
TEST the system for normal operation.
No GO to V4
.
V
4: CHECK THE APP SENSOR/MECHA
NICAL GUARD SENSOR REFERENCE VOLTAGE CIRCUIT FOR SHORT TO
GROUND
Turn the ignition swi
tch to the
OFF position.
1
Meas
ure the resistance between PI42, pin 04 (UW) and GROUND.
2
Is

the resistance less than 10,000 ohms?
Yes REPAIR the short circuit. For addi tional information, refer to the wiring diagrams. CLEAR the DTC.
TEST the system for normal operation.
No GO to V5
.
V
5: CHECK THE REFERENCE VOLTAGE AT THE THROTTLE POSITION SENSOR
Re

connect the ECM electrical connectors, EM10 and EM11.
1
Disc

onnect the TP sensor electrical connector, PI06.
2
Turn the ignition swi

tch to the ON
position.
3
Measure the
voltage between PI
06, pin 04 (UW) and GROUND.
4
Is th
e voltage less than 5 volts?
Yes GO to V6
.
No

GO to V7
.
V
6: CHECK THE THROTTLE POSITION SENSOR REFE
RENCE VOLTAGE CIRCUIT FOR HIGH RESISTANCE
Turn the ignition swi
tch to the OFF
position.
1
D
isconnect the ECM electrical connectors, EM10 and EM11.
2
Me

asure the resistance between PI06, pin 04 (UW) and EM10, pin 21 (UW).
3
Me

asure the resistance between PI06, pin 04 (UW) and EM11, pin 08 (UW).
4
Is either resi

stance
greater than 5 ohms?
Yes REPAIR the high resistance circui t. For additional information, refer to the wiring diagrams. CLEAR
the DTC. TEST the system for normal operation.
No GO to V7
.
V
7: CHECK THE THROTTLE POSITION SENSOR REFERENCE VOLTAGE CIRCUIT FOR SHORT TO HIGH VOLTAGE
Turn the ignition swi

tch to the ON
position.
1
Measure the
voltage between PI
06, pin 04 (UW) and GROUND.
2
Is th
e voltage greater than 6 volts?
Yes REPAIR the short circuit. For addi tional information, refer to the wiring diagrams. CLEAR the DTC.
TEST the system for normal operation.
No
GO to V8
.
V
8: CHECK THE THROTTLE POSITION SENSOR REFE
RENCE VOLTAGE CIRCUIT FOR SHORT TO GROUND
Turn the ignition swi
tch to the OFF
position.
1
Meas
ure the resistance between PI06, pin 04 (UW) and GROUND.
2
Is

the resistance less than 10,000 ohms?
Yes REPAIR the short circuit. For addi tional information, refer to the wiring diagrams. CLEAR the DTC.
TEST the system for normal operation.
No GO to V9
.
V
9: CHECK THE REFERENCE VOLTAGE AT THE FUEL TANK PRESSURE SENSOR
Di

sconnect the FTP sensor electrical connector, FP01.
1
Re

connect the ECM electrical connectors, EM10 and EM11.
2
Turn the ignition swi

tch to the ON
position.
3

Measure the voltage between FP 01
, pin 03 (UW) and GROUND.
4
Is th
e volt
age less than 5 volts?
Yes GO to V10
.
No
CHECK
for DTCs associated with
TP sensor, APP/mechanical guard sensor, or FTP sensor. INSTALL a
new sensor as indicated by the DTC. CLEAR the DTC. TEST the system for normal operation.
V
10: CHECK
THE FUEL TANK PRESSURE SENSOR
REFERENCE VOLTAGE CIRCUIT FOR HIGH RESISTANCE
Disc
onnect the battery negative terminal.
1
D
i
sconnect the ECM electrical connectors, EM10 and EM11.
2
Measure t

he resistance between FP01,
pin 03 (UW) and EM10, pin 21 (UW).
3
Measure t
he resistance between FP01,
pin 03 (UW) and EM11, pin 08 (UW).
4
Is either resistance greater
than 5 ohms?
Yes REPAIR the high resistance circui t. For additional information, refer to the wiring diagrams. CLEAR
the DTC. TEST the system for normal operation.
No GO to V11
.
V11: CHECK
THE FUEL TANK PRESSURE SENSOR REFE
RENCE VOLTAGE CIRCUIT FOR SHORT TO HIGH VOLTAGE
Re
connect the battery negative terminal.
1
Turn the ignition swi
t
ch to the ON
position.
2
Measure the voltage between FP 01
, pin 03 (UW) and GROUND.
3
Is th
e volt
age greater than 6 volts?
Yes REPAIR the short circuit. For addi tional information, refer to the wiring diagrams. CLEAR the DTC.
TEST the system for normal operation.
No GO to V12
.
V12: CHECK
THE FUEL TANK PRESSURE SENSOR
REFERENCE VOLTAGE CIRCUIT FOR SHORT TO GROUND
Turn the ignition swit
ch to the OFF
position.
1
Measure t
he resistance between
FP01, pin 03 (UW) and GROUND.
2
Is t
he resistance less than 10,000 ohms?
Yes REPAIR the short circuit. For addi tional information, refer to the wiring diagrams. CLEAR the DTC.
TEST the system for normal operation.
No CHECK for DTCs associated with TP sensor, APP/mechanical guard sensor, or FTP sensor. INSTALL a
new sensor as indicated by the DTC. CLEAR the DTC. TEST the system for normal operation.
PI
NPOINT TEST W : DTC P1243; SENSOR RE
FERENCE GROUND MALFUNCTION (THROTTLE
SENSORS, FUEL TANK PRESSURE SENSOR, ECT, IAT, IAT 2 SENSORS)
TE S
T
CONDITIONS
D E
TAILS/RESULTS/ACTIONS
W1: CHECK THE SENSO
R
REFERENCE
GROUND AT THE THROTTLE SENSORS
Disc
onne
ct the TP sensor electrical connector, PI06.
1
Meas
ure t
he resistance between PI06, pin 01 (BG) and GROUND.
2
Is th
e res
istance greater than 5 ohms?
Yes GO to W2
.
No
GO to W3
.
W2: CHECK TH
E THROTTLE SENSOR REFERENCE GROUND CIRCUIT FOR HIGH RESISTANCE
D
i
sconnect the ECM electrical connectors, EM10 and EM11.
1
Meas
ure t
he resistance between PI06,
pin 01 (BG) and EM10, pin 20 (BG).
2
Measure t
he resistance between PI06,
pin 01 (BG) and EM11, pin 12 (BG).
3
Is either resistance greater
than 5 ohms?
Yes REPAIR the high resistance circuit. For additional information, refer to the wiring diagrams. CLEAR the
DTC. TEST the system for normal operation.
No GO to W3
.
W3: CHECK THE SENSO R
REFERENCE GROUND AT
THE APP SENSOR/MECHANICAL GUARD SENSOR

Di
sconnect the APP sensor/mechanical guard sensor electrical connector, PI42.
1
Re

connect the ECM electrical connectors, EM10 and EM11.
2
Meas

ure the resistance between PI42, pin 02 (BG) and GROUND.
3
Is th

e resistance greater than 5 ohms?
Yes GO to W4
.
No

GO to W5
.
W4: CHECK THE APP
SENSOR/MECHANICAL GUARD SE
NSOR REFERENCE GROUND CIRCUIT FOR HIGH
RESISTANCE
D
isconnect the ECM electrical connectors, EM10 and EM11.
1
Meas

ure the resistance between PI42,
pin 02 (BG) and EM10, pin 20 (BG).
2
Meas
ure the resistance between PI42,
pin 02 (BG) and EM11, pin 12 (BG).
3
Is either resi
stance
greater than 5 ohms?
Yes REPAIR the high resistance circuit. For additional information, refer to the wiring diagrams. CLEAR the
DTC. TEST the system for normal operation.
No GO to W5
.
W5: CHECK THE SENSO
R REFERENCE GROUND AT THE FUEL TANK PRESSURE SENSOR
Di

sconnect the FTP sensor electrical connector, FP01.
1
Re

connect the ECM electrical connectors, EM10 and EM11.
2
Meas

ure the resistance between
FP01, pin 01 (BG) and GROUND.
3
Is th
e resistance greater than 5 ohms?
Yes GO to W6
.
No

GO to W7
.
W6: CHECK THE FUEL
TANK PRESSURE SENSOR RE
FERENCE GROUND CIRCUIT FOR HIGH RESISTANCE
D
isconnect the ECM electrical connectors, EM10 and EM11.
1
Meas

ure the resistance between FP01,
pin 01 (BG) and EM10, pin 20 (BG).
2
Meas
ure the resistance between FP01,
pin 01 (BG) and EM11, pin 12 (BG).
3
Is either resi
stance
greater than 5 ohms?
Yes REPAIR the high resistance circuit. For additional information, refer to the wiring diagrams. CLEAR the
DTC. TEST the system for normal operation.
No GO to W7
.
W7: CHECK THE SENSO
R REFERENCE GROUND AT THE ECT SENSOR
Re

connect the ECM electrical connectors, EM10 and EM11.
1
D

isconnect the ECT sensor electrical connector, PI04.
2
Meas

ure the resistance between PI04, pin 01 (BG) and GROUND.
3
Is th

e resistance greater than 5 ohms?
Yes GO to W8
.
No

GO to W9
.
W8: CHECK THE ECT SEN
SOR REFERENCE
GROUND CIRCUIT FOR HIGH RESISTANCE
D
isconnect the ECM electrical connectors, EM10 and EM11.
1
Meas

ure the resistance between PI04,
pin 01 (BG) and EM10, pin 20 (BG).
2
Meas
ure the resistance between PI04,
pin 01 (BG) and EM11, pin 12 (BG).
3
Is either resi
stance
greater than 5 ohms?
Yes REPAIR the high resistance circuit. For additional information, refer to the wiring diagrams. CLEAR the
DTC. TEST the system for normal operation.
No GO to W9
.
W9: CHECK THE SENSO
R REFERENCE GR
OUND AT THE IAT SENSOR (MAF)
Re
connect the ECM electrical connectors, EM10 and EM11.
1
Di

sconnect the IAT sensor (MAF) electrical connector, PI35.
2
Meas

ure the resistance between PI35, pin 04 (BG) and GROUND.
3

All vehicles are fitted with a stainless steel exhaust system which features:
Low back-pressure gas flow. Catalytic converters for mark ets having unleaded fuel. Front muffler common to the left-hand and right-hand engine cylinder banks.
Downpipe Catalytic Converter Assembly

Fuel System - General Inform
ation - Fuel System
Description an
d Operation

The fuel tank is mounted across the vehicle behind the passenger compartment bulkhead.
Fuel is drawn by the fuel pump from the tank and then supplied to the two fuel rails, via a filter.
Fuel injectors are installed in the fuel ra ils on each side of the intake manifold.
The amount of fuel injected into th e engine is controlled by the ECM.
A cross-over pipe connects the two fuel ra ils together at the front of the manifold.
A test valve in the cross-over pipe allo ws the fuel rail to be pressurized and de-pressurized during the servicing and
troubleshooting procedures.
A pressure regulator on the rear of the right fuel rail controls the pressure in the fuel rails.
A return line directs excess fuel from the pressure regulator back to the fuel tank.
Operation and service procedures
The fuel injector
s, rails, pres
sure regulator and, wher e fitted, supercharger are described in greater detail in Section 303-04
together with servicing procedures.
The fuel tank, pump, fuel level senders and fuel lines are similarly covered in Section 310-01.

Fuel System - General Information - Fuel System Pre
ssure Check
Gen
eral Procedures
WARNING: Working on the fuel system re sults in fuel and fuel vapor being present in the atmosphere. Fuel vapor is
extremely flammable, hence great care must be taken whilst working on the fuel system. Adhere strictly to the following
precautions:
D
o not smoke in the work area
Di

splay
NO SMOKING signs around the work area
D
isconnect the battery before
working on the fuel system
Av
oid sparks
Make sure sui

table fire ex
tinguishers are at hand
Make sure absor
bent material is at
hand to soak up any spillage
Make sure the work area is
well ventilated
M

ake sure that the gauge is correctly conn
ected, and that all connections are secure BEFORE starting the engine
DO N
OT
disconnect the gauge from the schrader valve while the engine is running
Make su
re the schrader valve reseals once the gauge is disconnected
• NOTE: Depending on the design of the ga uge set, there may be a drain valve and tube. Make sure this valve is closed, and
the drain tube placed in a suitable container BEFORE connecting the gauge to the schrader valve.


1. Make sure the vehi
cle is in
Park for vehicles with automatic
transmission, Neutral for vehicles with manual transmission.
2. Apply the parking brake.
3. Place suitable absorbent material around the schrader valve to
absorb any spillage when connecting the gauge set.
4. Remove the protective cap from the schrader valve.
5. Connect the gauge, using adaptors if required.
6. Remove the absorbent material and dispose of safely.
7. Disconnect and plug the vacuum hose from the pressure
regulator.
8. Start the engine and record the fuel pressure reading.
As a gui
de, the fuel pressu
re should be approximately 3.0
bar (44.1 psi) with the regulator disconnected.
9. With the engine still running, reconnect the vacuum hose to
the pressure regulator an d record the reading.
Th
e pressure should dr
op to approximately 2.6 bar (38
psi) when the vacuum hose is reconnected.
10. Switch off the engine.
11. Place more absorbent material around the schrader valve.
12. Where fitted, open the drain valve and allow the fuel from the
gauge and line to flow into the container to depressurize the
system.
13. Disconnect and remove the gauge set and any adaptors.
14. Clean up any fuel which may have been spilt and remove the
absorbent material. Dispose of safely.
15. Refit and secure the protective cap to the schrader valve.
16. Reconnect the fuel pressure regulator vacuum hose.
17. Start the engine and make sure there are no leaks.

Fuel System - General Information - Fuel System Pressure Rele
ase
Gen
e
ral Procedures


S p
ecial Tool(s)

Tes
t
Equipment - Fuel Pressure Relief
310-058 (TE 7635A or JD 209)
1. WARNING: BEFORE PROCEEDING, IT IS ESSENTIAL THAT
THE WARNING NOTES GIVEN IN SECTION 100-00 (UNDER THE
HEADING 'SAFETY PRECAUTIONS') ARE READ AND
UNDERSTOOD.
Open engine compartment and fi t paintwork protection sheets.
2. Carefull
y remove left
hand engine cover, taking care not to
damage the plasti c fixings or the rubber inserts.

3. WA
RNING: MAKE SURE EQUIPMENT BLEED / DRAIN
VALVE IS CLOSED.
• NOTE: Place a cloth under the valve to collect any spillage.
Depressurize fuel system.
Make sure ignition i s
switched off.
R
e
move cap from Schrader valve.
Pla
c
e a closed container, su
itable for collecting fuel,
adjacent to vehicle.
R e
move lid from container.
Conne
ct
fuel injection pressu
re test equipment 310-058
(TE 7635A or other suitable type).
Insert drain / bleed tu be i
nto fuel container.
R
e
ad and follow manufacturer's instructions to
depressurize fuel system.
4. Store drained f u
el safely and make
sure container lid is closed
securely.
5. Remove equipment and discard cloth from beneath the valve.
6. Install valve cap.
7. Install left hand engine cover.